Flexible grinder or sander



Sept .28, 1943- J. G. FLoRAcK v l 2,330,209

, FLEXIBLE GRINDER OR SANDER Filed Oct. 5, 1941 Mmmm IIIIIII l IN V ENTOR.

Josep/1 Florac/c BY AQIEY.

Patented Sept. 28, 1943 `FLEXIBLE GRINDER on SANDER Joseph George Florack, Hackensack, N'. T.

Application October 3,

8 Claims.

The object of this invention is to provide a flexible rotary core and chuck that is easily covered with cloth or paper coated with abrasive material, in which the flexible core can yield under pressure and still maintain a support for the abrasive cloth, or paper, or other material carried thereon that is rm enough to make it effective for grinding or polishing.

Another object of the invention is to use for the flexible core an ordinary rubber cork of several inches in diameter and perforated centrally, which is carried on a spindle between two metal discs and can be compressed between the discs for the purpose of expanding it diametrically.

Another object of the invention is to provide a closed metallic ring' or' band with one or more flexible strips between it and the rubber core, which strips on the expansion of the rubber core will be securely clamped in the assembly and made substantially integral therewith when at rest or when rotated at any speed.

Another object of the invention is to make the metallic band comparatively narrow and the abrading strips comparatively wide, so that a large part of the surface of the abrading strip will be exposed at the side of the band.

Another object of the invention is to make the assembly so the abrading strips can be assembled thereon singly or in multiple layers.

Another object of the invention is to make the device so that after the abrading surface has become worn, the abrading strip can be removed and the worn surface can be clamped under the metal band, and the abrading surface previously covered by the metal band can be exposed at the side of the band and used for grinding or polish- Another object of the invention is to roughen the under surface of the metal band I6 so that' it will take better hold on the abrading strip. This may be done by makingr prick marks on the outside of the metal band, or in any other suitable manner.

Another object of the invention is to provide circumferential grooves on the rubber core to roughen the surface thereof and increase its gripping effect.

These and other objects of the invention will be illustrated in the drawing, described in the specification, and pointed out in the claims at the end thereof.

In the drawing:

Figure 1 is a side elevation of the assembly band to which is attached the abrasive' cloth or paper.

1941, Seal No. '413,469

(Cl. l.'51--1940 Figure 2 is a side elevation of the supporting unit assembled without the abrasive band.

Figure 3 is an end elevation of the assembly shown in cross section in Figure 4.

Figure 4 is a cross section on the line 45t-Ir of Figure 3.

Figure 5 i's a sectional elevation of the assembly band, enlarged, the section being taken on a line similar to the line ltr- 4x of Figure 3.

Figure 6 is a sectional elevation of the assembly of the metallic band, and steel abrading strip, and the supports therefor other than the rubber core.

In the drawing like reference numerals indicate like parts'.

In the drawing reference numeral I indicates a 'stud or shaft-having a nexagon shoulder or boss 2 formed on the shaft and integral therewith. The other end of thes'haft is threaded as indicated at 3. On this shaft is placed a supporting disc plate 4 and a back plate 5. On the threaded end of this shaft I- is next placed a rubber Core 6, which core makes a tight fit with the threaded part 3 'of the shaft I. This core is tapered and is likev an ordinary rubber cork with a hole in the center. These three'parts, namely, li, 5, and 6, a-r'e held together by three screws 1 placed 120 degrees apart. Next on the shaft is loosely placed the disc 8, which is in the form of a washer and is of somewhat smaller diameter than the disc 5. Next to the plate 8 is placed the washer 9, which is similar to the back supporting plate 4. n the end of the shaft is threaded the control nut I0. As this nutr is turned, the rubber core 5 is compressed between the discs 5 and I3 and isl pressed both inwardly firmly against the threaded part 3 of the shaft I and outwardly into engagement with the sleeve that will new be deseribed.- This rubber core E is preferably grooved with aseries of peripheral grooves for a purpose that will be described presently.

the rubber core is a cylindrical sleeve that is built up of or is composed of one or more fabric layers of sufficient stiffness and flexibility to provide a yielding surface. 4One of these layers II, namely, the inside one, is preferably of flexible glass or so-called lumarith material. The nextouter layer I2 is a flexible cardboard cushion strip. Surrounding these is a exible paper or cloth layer I4 coated with fine emrgy grinding' surface, and outside of this may be another layer I5 of Hexible paper or cloth covered with coarse emery or carborundum. All of these' layers have overlapping ends instead of abutting ends, with the overlaps of one layer staggered with reference to the overlaps of the preceding and succeeding layers. Surrounding one end of these cylindrical strips is an endless cylindrical metal band I6. This assembly normally makes a close sliding fit with the rubber corey and the end of it may abut against the disc 5 or it may be placed some distance to the left of the disc 5 as that disc is shown in Figures 2 and 4.

Before thenut I is tightened up, this assembly shown in Figures 1 and 5 is slipped over the rubber core, so that the end thereof abuts against the disc 5 or is placed in line with one of the grooves or ridges. Then the nut IIJ i's turned, so as to compress the rubber core between the discs 5 and 8, causing the rubber core to expand radially in and out and causing it' to take a firm hold on the screw end of the shaft I and also causing it to take a firm hold in the sleeve assembly II, I2 and I4, so that the sleeve assembly rotates with the rubber core, as though it were integral therewith.

The peripheral grooves and ridges on the outside of the rubber core take a better grip on the sleeve assembly and act as a gauge when the assembly does not make contact with the disc 5.

The rubber core is tapered like an ordinary rubber cork, while the interior and the exterior of the sleeve is cylindrical. This leaves a tapering or wedge-shaped open space between a part of the rubber core and the sleeve, permitting the abrading sleeve to yield under pressure while it rotates and make contact with a. somewhat flattened abrading surface.

The shaft I is driven in any suitable manner, so that the assembly rotates at high speed. If driven with a flexible shaft the assembly is portable, As the grinding or polishing surface bears against the surface that is to be polished, or as the surface to be polished bears against it, the flexible bands yield sucient to give uniform, firm grinding or polishing contact. The assembly can be used for grinding, filing, sanding, and finishing all kinds and types of metal and wood surfaces, and can be used on external as well as internal surfaces or contours.

The assembly of the abrading surfaces and the backing strips therefor can be varied in a great variety of ways according to the material at hand or the job to be Worked on. It is possible to use in this assembly a exible steel strap le, line cut, for the outer layer, which strap will be backed by various flexible layers, for which purpose more especially a stiff rubber backing strip is found desirable next to the file strip, which rubber backing will in turn be supported by lumarith, or flexible glass, or cardboard, or any other suitable materia-l, these layers being shown for example in Figure 6, in which the outer layer is the file strip and is indicated by numeral I1, I8 indicating the rubber strip, and I9 indicating the assembly of any other backing strips that may be desired.

It will also be understood that after any abrading surface has become worn, that particular strip can be removed from the assembly, and the worn surface can be placed under the metal band and clamped in place thereunder, leaving the fresh abrading part exposed for use in the assembly.

While I have shown a rubber core that is coneshaped, it will be understood that the rubber core can be cylindrical, and when expanded under pressure by turning the nut I0 will grip the abrading material and rotate it.

It is also obvious that an expanding metal mandrel may be used to clamp the abrading strips inside of the ring or band, and such use is within the scope of my invention.

In order to more eifectually grip the abrading strip by the metal band, I provide prick marks in the metal band which raise the surface of the metal on the inside of the band, or the inner surface of the band may be roughened in any other suitable manner. These prick marks are indicated by the reference numeral 2|.

I claim:

l. In a flexible grinder the combination of a wide flexible strip having a grinding surface arranged in cylindrical form, a spindle at the center of said grinding surface said spindle being threaded at one end, a disc xed on said spindle at an intermediate part thereof, a tapered rubber core carried on the spindle at the threaded end thereof with its big end placed at the disc and with its small end spaced apart from and inside of the grinding surface with an open space between them, a ring loosely surrounding the big end of the rubber core, the cylindrical flexible strip having one edge placed between the rubber core and the ring, means for expanding the rubber core to grip part of the grinding surface between the rubber core and the ring, the rest of the grinding surface being exposed the the side of the ring and means for rotating the assembly.

2. In a iiexible grinder, an assembly comprising a spindle, a disc fixed thereon, a tapered rubber core carried on the spindle with its big end against the disc, a narrow metallic ring loosely surrounding the big end of the rubber core, a wide plane strip of abrading material wrapped around the big end of the core substantially in the form of a cyl 'nder, and having one edge placed between the rubber core and the metallic ring, means for expanding the big end of the rubber core to grip part of the strip of abrading material between the rubber core and the metallic ring, part of the strip of abrading material being exposed at the side of the metallic ring in substantially cylindrical form and spaced apart from the small end of the rubber core. means for rotating the assembly.

3. In a flexible grinder, an assembly comprising a threaded spindle, a disc xed therean, a tapered rubber core carried on the spindle with its big end against the disc, a narrow metallic ring loosely surrounding the big end of the rubber core, a wide plane strip of abrading material wrapped around the big end of the core substantially in the form of a cylinder, having one edge placed between the rubber core and the metallic ring, a washer and a nut engaging the threaded end of the spindle, the rubber core being compressed along its axis between the washer and the disc on the turning of the nut on the threaded spindle, the big end of the rubber core being expanded radially thereby and gripping part of the strip of abrading material between the rubber core and the metallic ring, the rest of the strip of abrading material being exposed at the side of the metallic ring substantially in cylindrical form and spaced apart from the small end of the rubber core, means for rotating the assembly.

4. In a flexible grinder an assembly comprising a threaded spindle, a disc xed thereon, a rubber tapered core carried on the spindle with its big end against; the disc, a narrow metallic ring loosely surrounding the big end of the rubtween the rubber core and the metallic ring, theV ber core, a wide plane strip of abrading material wrapped around the big end of the core substantially in the form of a cylinder having on/e edge placed between the rubber core and the metallic ring, exible backing'strips placed between the abrading strip and the rubber core and supporting the exposed part of the abrading strip and the rubber core, a Washer and a nut engaging the threaded end of the spindle, the rubber core being compressed axially between the washer and the disc on the turning of the nut on the threaded spindle, the big end of the rubber core being expanded radially thereby and gripping part of the strip of abrading material and the backing strips'between the rubber core and the metallic ring, the rest of the strip of abrading material and supporting strips being exposed at the side of the metallic ring substantially in cylindrical form and spaced apart from the small end of the rubber core, means for rotating the assembly.

5. In a flexible grinder the combination of a narrow metal band, an expandible tapered core inside of the band, means for expanding the big end of the core, a wide flexible abrading strip clamped between the band and the core along one edge thereof, part of the strip of abrading material being exposed in the form of a cylinder at the side of the band and holding itself apart from the small end of the core, means for rotating the combination.

6. In a flexible grinder a spindle having a disc xed thereon intermediate the ends thereof, one end of the said spindle being threaded, a tapered soft rubber'core carried on the threaded end of the spindle with its big end placed adjacent to the disc, a narrow metal ring loosely surrounding the big end of the rubber core, a wide plane strip of abrading material wrapped around the big end of the core substantially in the form of a cylinder and having one end of the cylinder placed between the large end of the rubber core and the metallic ring, means for compressing the rubber core along the spindle and causing it to expand diametrically at the big end and grip the end of the cylinder of abrading material berest ofthe strip of abrading material being exposed at the side of the metallic ring, and vmeans for rotating the assembly.

7. In a exible grinder the combination of a spindle having a disc fixed intermediate the ends thereof, one end of said spindle being threaded, a tapered soft rubber core having a hole along the axis thereof with which it closely engages the threaded end of said spindle, a narrow ring surrounding the large end of the core and abutting against the washer, a plane strip of `abrading material preferably rectangular in shape wrapped around the big end of the core substantially in the form of a cylinder, one end of the cylinder being placed between the ring and the large end of the core, means for compressing the core along the spindle and against the washer for the purpose of expanding thev large end of the core and thereby clamping the end of the cylinder of abrading material between the periphery of the large end of the core and the ring and means for rotating the assembly. ,v

8. In a exible grinder the combination of a spindle having a disc xed intermediate the ends thereof, one end of said spindle being threaded,v

a tapered soft rubber core having a hole along the axis thereof with which it closely engages the threaded end of said spindle, a narrow ring surrounding the large end of the core and abutting against the washer, a plane strip of abrading material preferably rectangular in shape and wrapped around the big end of the core substantially in the form of a cylinder, one end of the cylinderbeing Vplaced between the ring and the large end of the core, means for compressing the core along the spindle and against the washer for the purpose of expanding the large end of the core and thereby clamping the ,end of the cylinder of abrading material between the periphery of the large end of the core and the ring, the other end of the cylinder of abrading material being left unsupported internally by the small end of the core and means for rotating 45 the assembly. 

